From: | Christopher Kings-Lynne <chriskl(at)familyhealth(dot)com(dot)au> |
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To: | Harry Jackson <harryjackson(at)gmail(dot)com> |
Cc: | pgsql-performance(at)postgresql(dot)org |
Subject: | Re: PostgreSQL performance question. |
Date: | 2005-12-15 02:02:18 |
Message-ID: | 43A0CEAA.6060800@familyhealth.com.au |
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Thread: | |
Lists: | pgsql-performance |
> I have been using PostgreSQL (currently 7.4.7) for several years now and
> am very happy with it but I currently run a website that has had a
> little bit of a boost and I am starting to see some performance problems
> (Not necessarily PostgreSQL).
PostgreSQL 8.1.1 should give you greater performance...
> The database has been allocated 2Gb worth of shared buffers and I have
> tweaked most of the settings in the config recently to see if I could
> increase the performance any more and have seen very little performance
> gain for the various types of queries that I am running.
That sounds like far too many shared buffers? I wouldn't usually use
more than a few tens of thousands, eg. 10k-50k. And that'd only be on
8.1 that has more efficient buffer management.
> Get it into RAM hence the slight delay here. This delay has a serious
> impact on the user waiting in the web application.
>
> # select * from test where text = 'uk' ;
> Time: 477.739 ms
You need to show us the explain analyze plan output for this. But 477ms
is far too slow for an index scan on a million row table.
> max_fsm_pages = 500000 # I am thinking this might be a bit low.
> max_fsm_relations = 1000
Maybe do a once-off vacuum full to make sure all your tables are clean?
Chris
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